Hospital mortality rates unreliable, research finds

October 18, 2012

(Medical Xpress)—A brand new study by the University of Birmingham suggests that the system used by the Government to inform key decisions about the performance of NHS hospitals is inadequate.

Research published online today in the journal BMJ Quality and Safety shows that Standardised Mortality Ratios (SMRs) are not a reliable indicator of the quality of hospital care and therefore should not be used to trigger inquiries such as the high-profile probe being conducted into the performance of Mid Staffordshire Hospital.

A recent academic paper concluded that an observed lack of agreement between different methods for calculating hospital-wide mortality rates may result from 'fundamental flaws in the hypothesised association between hospital-wide mortality and quality of care.' Such a flaw would arise if preventable deaths were low in relation to inevitable deaths.

The Birmingham team's paper models the correlation between overall risk-adjusted deaths and deaths due to poor care. The researchers developed a mathematical model - which was vetted and verified by international referees - to estimate the proportionate variation in SMRs that can be accounted for by fluctuations in preventable deaths.

'The relationship between overall mortality and deaths preventable by better care is not linear,' explains Professor Richard Lilford, Professor of Clinical Epidemiology at Birmingham and lead author of the study. 'The signal (preventable deaths) gets lost in the noise (inevitable deaths) unless more than a quarter of all deaths are preventable. 'The appalling idea that one in four of all NHS hospital deaths are preventable is not backed up by current evidence and does not make sense given that we all have to die and nearly half of us do so in hospital.'

'It may be an inconvenient truth but we are saying that even when you have obtained risk-adjusted figures, they are still not a good measure of quality unless a large proportion (over 25 per cent) of the overall deaths are preventable. Therefore, we should not study overall mortality rates, even as a survey tool, in situations where people are going to die anyway.' says Professor Lilford.

'The fallacy is to assume that by doing the risk-adjustment process you have solved the problem,' he adds. 'This model offers a reality check for case-mix adjustment schemes designed to isolate the preventable component of any outcome rate. We would advise caution about using overall rates of mortality even after risk adjustment. It is preferable to look directly at quality of care.'

Related Stories

Hospitals, health insurers and patients often rely on patient death rates in hospitals to compare hospital quality. Now a new study by researchers at Yale School of Medicine questions the accuracy of that widely used approach ...

(Medical Xpress) -- There are almost 12,000 preventable deaths in hospital every year due to problems with care but this is less than a third of the number previously thought, according to new research.

Recommended for you

It is known that sleep facilitates the formation of long-term memory in humans. In a new study, researchers from Uppsala University now show that sleep does not only help form long-term memory but also ensures access to it ...

Fish oil is one of the most popular dietary supplements in the U.S. because of the perceived cardiovascular benefits of the omega-3 it contains. However, scientific findings on its effectiveness have been conflicting. New ...

A new study by researchers at the University of Colorado, New York University, and the University of North Carolina at Chapel Hill estimates the number of deaths that can be linked to differences in education, and finds that ...

Columbia University scientists have developed a computational method to investigate the relationship between birth month and disease risk. The researchers used this algorithm to examine New York City medical databases and ...

(Medical Xpress)—A team of researchers with Newcastle University in the U.K. has found no evidence of balance or coordination impairments in people watching a stereoscopic (3D) movie on a television screen. In their paper ...

When Americans go out to eat, either at a fast-food outlet or a full-service restaurant, they consume, on average, about 200 more calories a day than when they stay home for meals, a new study reports. They also take in more ...

0 comments

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.